Circulator can redefine HVAC industry with inbuilt duo-sensor

While it is the “most sophisticated circulation pump to date,” the Grundfos MAGNA3 is apparently still ahead of its time, according to Anders Nielsen, Commercial Business Applications Manager at Grundfos.

The MAGNA3 can increase system resilience and efficiency and cut energy use in applications ranging from heating and cooling to hot tap water recirculation. Yet, like a smartphone that is only used for phone calls or a wrench that is only used on kitchen sinks, the MAGNA3’s versatility in HVAC systems has yet to be fully realised by some of its users.

“Grundfos has created a sort of Swiss Army Knife of pumps, but most are still only using it like a simple butter knife,” he says.

PHOTO: The MAGNA3’s integrated sensor (light blue highlight) measures differential pressure over the pump for increased efficiency. It also measures temperature, which can be used for optimising hot water recirculation, among other uses. Source: Grundfos

The key to its intelligence and versatility lies in its built-in, duo-sensor, which monitors pressure and temperature. Additionally, users can commission it simply and monitor the pump and system's activity in real time via a smartphone and the Grundfos GO app.

The Swiss Army Knife in action

In order to illustrate the versatility of the MAGNA3, Anders Nielsen outlines three diverse scenarios that previously might have needed three different pump types.

The first requires the installation of a pump connected to a mixing loop in a radiant cooling system. With a fixed-speed pump, pressure problems could result from the significant variations in flow.

PHOTO: A characteristic mixing loop of a radiant cooling system.

FIGURE 1: Pressure Changes According to Flow (Fixed-Speed Pump). With an ordinary fixed-speed pump, pressure increases from nominal to maximum when flow decreases due to valve closure.

By installing a MAGNA3 and setting it to Constant Pressure mode, however, the pump speed fluctuates along with flow to deliver the exact pressure the system requires, says Anders Nielsen.

FIGURE 2: Pressure Changes according to Flow (MAGNA3). With the MAGNA3 set to Constant Pressure mode, pressure remains at the nominal level, despite variations in flow.

While other pumps also have a constant pressure function, he adds, the MAGNA3 boasts a number of additional built-in characteristics, such as a differential pressure sensor, that help to save energy and building overall system resilience by eliminating excess pressure and the risk of by-pass.

“Grundfos has created a sort of Swiss Army Knife of pumps, but most are still only using it like a simple butter knife.”

Anders Nielsen, Commercial Business Applications Manager at Grundfos.

The MAGNA3 can also be set up to use Constant Pressure via Grundfos GO, a mobile pump management application that can be downloaded to iOS or Android devices.

When pressure varies exponentially depending on flow

The second scenario requires a pump for a heating application in a commercial building with an extensive network of radiators. Unlike the radiant cooling example, this system involves a much farther distance from the pump to the final consumer (figure 3), causing pressure to vary exponentially depending on flow (figure 4).

FIGURE 3: Extensive Radiator System in a Commercial Building. Due to the distance from pump to final consumer, pressure can vary widely depending on the flow.

FIGURE 4: Pressure Variations in Radiator Heating Systems. According to the Laws of Affinity, when flow drops from 25 to 12.5 m3/h, the related pressure drops by a factor of four, from 10 to 2.5 Meter Water Columns (mWc).

FIGURE 5: Pressure Variations in Radiator System (MAGNA3). The MAGNA3 contains an internal sensor that measures and controls the Delta P, the difference between pressure (delivery) and suction (income), in order to meet the needs of different valves throughout the system, according to Anders Nielsen of Grundfos.

According to Anders Nielsen, if the MAGNA3 is set to Proportional Pressure mode, the exact pressure requirements are met regardless of valve position (figure 5) - another intelligent feature. This is because the MAGNA3 contains an internal sensor that measures and controls the Delta P, the difference between pressure (delivery) and suction (income), in order to meet the needs of different valves throughout the system.

In addition to building system resilience by relieving excessive pressure, the pump has a built-in work log that accumulates and monitors data, as well as an optional, additional temperature sensor that can optimise energy usage, he says.

PHOTO: The built-in temperature sensor in the MAGNA3 ensures that no more water than necessary is circulated during and after working hours, says Anders Nielsen.

Improving efficiency in hot water circulationIn the third scenario, a circulation pump is required in a commercial building to maintain hot water availability while taps are not running. In addition to regulating usage during working hours, the building’s owner wants an on/off timer to shut the pumps down when the building is empty. While it is possible to connect a timer to the MAGNA3, it is unnecessary. A user only has to set it to Constant Temperature mode, which measures the system’s temperature in real time, says Anders Nielsen.

“The built-in temperature sensor ensures that no more water than necessary is circulated during and after working hours,” he says.This alone can save building owners a significant amount of money. According to studies (in Danish) by the Danish Building Research Institute, recirculation can account for more than 50% of the overall hot water-related energy consumption in commercial buildings.

Systems Thinking

The MAGNA3’s built-in sensor collects data on temperature, time, pressure, quantities and energy consumption. These steps toward intensified control and monitoring are part of the Grundfos iSOLUTIONS (intelligent solutions) program.

Grundfos iSOLUTIONS refer to a shift away from a conventional, component-based approach to one that looks at the complete system. While the MAGNA3 alone can prove to increase efficiency and reduce energy consumption in varied applications, the whole system of solutions make the real difference, says Anders Nielsen.

“Grundfos has already reduced the energy consumption of the MAGNA3,” he says. “But in reality, the energy cost of the pump is only a fraction of that of other components, such as boilers. The pump improves efficiency at the system level and can shave percentage points off the cost of other parts. That is where the real savings lies. That is the future.”

PHOTO: Through Grundfos GO, users can access real-time information on flow, energy consumption, temperature and more. In addition, they can manage the MAGNA3 remotely. In this scenario, the pump can be set to Constant Temperature mode and users select the precise set point by sliding the bar up or down.